1. Field of the Invention
The invention relates to a method of irradiating a target region by means of ultrasound, a position of the target region being determined by means of a magnetic resonance method. The invention also relates to a device for carrying out such a method.
2. Description of the Related Art
A method of this kind is known from U.S. Pat. No. 5,307,812. The known method is used to heat the target region of an object, for example within the body of a patient, by means of ultrasound. To this end, an MR image is formed wherefrom an operator derives the position of the target region. Subsequently, the focal region of the ultrasound to be generated is adjusted so as to be situated within the target region. After activation of the ultrasound source, the target region is heated by the ultrasound generated. In order to monitor the heating process, subsequently a temperature-position profile of the target region is determined by means of magnetic resonance. An operator derives the position of the focal region from the temperature-position profile. The operator can subsequently readjust the position of the focal region. An application of this known method can be found, for example in the field of cancer therapy in which a tumor within the body of the patient is heated, thus destroying the tumor cells.
It is a drawback of the known method that, when the target region of the body moves, for example due to the patient's respiration, body tissue which does not belong to the target region is moved into the focal region, so that it is undesirably heated by the ultrasound.